The invention relates generally to electro-optical communications and switching systems and more particularly to an electro-optical switching system employing a radio frequency electromagntic coupling.
It can be appreciated that there are many functions which particular persons or persons particularly situated cannot readily and conveniently accomplish by the use of hands, or other bodily movements, or by voice control. These individuals include persons who are physically handicapped to the extent of not having the use of their hands, limbs, or voice and those that while having all of their normal faculties are so engaged or otherwise constrained so as to be unable to effectively perform or control certain desired tasks. The latter category would include persons having both hands and perhaps both feet engaged in controlling machinery which requires additional control information from the operator.
In the field of handicap communications systems, a variety of additional body outputs have been used to control a communications systems. For example, prior art handicap communications systems are found that utilize such body outputs as breathing, tongue pressure or movement of the hand, leg, head, eye or some other controllable portion of the body for actuating the system. In many of these prior art communications devices the user is required to learn a new language and implementing the language or code of the device is often fatiguing. In one prior art electro-optical handicap communications system the eye motion of an operator is used to operate a keyboard-like accessory. The keyboard accesory includes a plurality of infrared responsive sensors disposed in a keyboard-like array. An infrared source is then directed into the eyes of the user who selectively actuates elements on the keyboard by dwelling his eyes upon an infrared responsive sensor on the keyboard. Infrared energy reflected from the operator's eye to the keyboard actuates the infrared responsive sensor to which the operator directs his eyes. By selectively dwelling his eyes upon various elements on the keyboard, the operator may assemble a message. While a great number of users may use this device regardless of the extent of their disability and without the need of learning a machine language, the system is prone to interference from environmental sources of light and can become completely inoperable under certain lighting conditions. Other electro-optical keyboard communications devices have employed infrared and other light energy sources mounted directly on the head of the user. In this case, the user directs the source of light energy to a desired photosensitive element with head movement. However, these devices are also subject to light interference problems and all of these systems require provision of an active photosensitive keyboard which is expensive.
The development of larger and faster aircraft both commercial and military has resulted in an increase in the number of sophisticated and complex airborne avionics systems which have substantially increased the amount of cockpit instrumentation and the workload of the crew of the aircraft. Furthermore, often these new avionic systems, which include navigational aids, engine performance monitoring systems and automatic flight control systems, require some type of constant actuation during flight. The proliferation of such avionic equipment is most evident in modern military aircraft where in addition to such systems as navigation and engine control, sophisticated radar systems and weapon delivery systems are provided. While commercial and military pilots are trained to manually operate these systems, often critical flight regimes are encountered when the activities required in manually switching the various cockpit instrumentation may cause a measurable reduction in the operational effectiveness and subsequently in the flight safety margin maintained by the pilot. Although the problem may be more severe in a military aircraft involving a single pilot where critical airborne operations include air-to-air refueling, low level flight, aircraft carrier landing and takeoff, ordinance delivery patterns and air combat maneuvering, the commercial pilot is similarly burdened with the work load and concentration involved in landing and taking off from congested commercial airports. The prior art has attempted to alleviate this problem with electro-optical switching systems including a plurality of photosensitive visually actuated switches. Each of the switches is used to control one of a plurality of avionic systems. The switches are infrared sensitive and the pilot is provided with a helmet including means for generating a collimated beam of infrared energy which the pilot directs to the photosensitve switches with a helmet mounted reticle. However, these systems do at times encounter environmental light source interference problem and involve the cost and complexity of installing control switches which are both photosensitive and manually actuable.
The art of tracking remote objects with electromagnetic radiation is highly developed. Prior art remote object position and orientation locators have employed a plurality of independent radiating antennas defining a source of electromagnetic radiation; a plurality of independent receiving antennas having a known relationship with respect to a remote object and means associated with the receiver for measuring the components of the received electromagnetic fields for calculating remote object position and orientation. Such systems may be used for example for guiding an aircraft to a landing site, guiding an excavating device, or tracking targets and aiming ordinance. In the latter case, the source of electromagnetic radiation is fixed with respect to the frame of the aircraft and the receiver is mounted on the pilot's helmet in a calibrated relationship with respect to a helmet mounted reticle. The analyzing means associated with the receiver repetitively calculates the position and orientation of the pilot's head with respect to the air frame and the pilot visually designates and/or tracks the target with the helmet mounted reticle to initially aim the ordinance. Purely optical systems for carrying out the same functions are also found in the environment of an aircraft cockpit employing a plurality of cockpit mounted infrared sources and a plurality of helmet mounted photodectors. Analyzing means connected to the pilot's helmet mounted photodetectors uniquely establish the position and orientation of the pilot's helmet. However, the optical versions of these systems are sensitive to light interference and function accurately within a very limited range of operator movement. Neither the light or radio frequency electromagnetic energy coupled systems as they exist are capable of functioning as an electro-optical communications and remote switching device.